Most important is getting the arrow in the right spot !!
Watch the animal as long as possible and remember where you lose sight of it.
Then mark the spot you shot from, visualize the shot and look for reference spots, for when you go to look for your arrow.
Leave it alone for at least a half hour before looking for arrow and/or blood.
I believe the #1 reason a wounded elk "gets away" is because it was followed up too soon after shot and spooked.
Of course this has resulted in some pretty intense debates, but I would rather find a dead elk after leaving it lay for a while than watch one get up and run away while looking for an arrow, or following a blood trail.